This invention relates to devices and arrangements for holding various types of cables. In particular, this invention relates to a cable retainer and corresponding organizer for arranging and retaining electrical cables and optical fibers.
As optical technology matures, an increasing number of devices use optical signals to transmit information. For example, communications equipment uses optical signals to transmit voice and other data over optical fibers between terminals and subscribers. At the same time, many of the active optical components necessary for generating and processing such optical signals require electrical power. Furthermore, not all signal processing circuitry can transition to optics at the present time. Hence, modern telecommunications modules as well as many other circuits tend to be hybrid, combining both electronics and optics.
Hybrid circuits require interconnection with electrical cabling, e.g., copper wires, as well as optical cabling, e.g., optical fibers. Both of these cable types have to be properly routed to the corresponding electrical and optical sub-assemblies or circuits. Electrical and optical sub-assemblies or circuits frequently reside in the same housing or module. When they do, the module has separate receptacles for plugging in the corresponding cables. In some cases, e.g., in large-scale digital communications terminals having a number of modules, many electrical and optical cables have to be plugged into each module.
Electrical and optical cables have different operating parameters and mechanical properties. Hence, managing and routing a large number of them to their destinations, e.g., in a large scale digital communications terminal presents a challenge.
Optical fiber is very sensitive to bending and kinking while electrical cabling, in general, is not. Optical signals traveling through the waveguide constituting the core of the optical fiber experience increasing losses and attenuation with bending. At a certain critical radius of curvature the optical fiber will experience complete signal loss because all light will leak from the core. In addition, optical fiber is brittle and susceptible to breaking even before reaching the critical radius of curvature.
U.S. Pat. No. 5,715,348 to Falkenberg et al. teaches a fiber management system for routing optical fibers having a minimum bend radius. This management system uses fiber trays with fiber guides having finger portions for retaining the optical fiber. At least one of the fingers has a curved portion with a radius selected to ensure that the optical fiber does not bend past its minimum bend radius when routed over the finger. Also, the fiber tray has a curved lip serving the same purpose. Other prior art include optical fiber splice protector, optical fiber coiling clip, optical fiber network saddle and slotted wiring ducts, e.g., as made by Richco, Inc.
Although the fiber management system taught by Falkenberg et al. is suitable for use in conjunction with racks of modules it does not address the problems encountered in organizing and routing large numbers of optical and electrical cabling simultaneously. Specifically, Falkenberg""s system is not practical for arranging and routing cables to their plug-in terminals in the individual modules. The other prior art elements suffer from the same limitations.
In addition to the above problems, optical fibers are susceptible to degradation caused by the leaching of plasticizers from PVC of which their jackets are made. It would thus represent an advance in the art to provide a system capable of organizing and routing electrical and optical cables in situations where a large number of cables and high cable densities are involved. Additionally, it would be a further advance if such system were designed to take into account the different operating and mechanical requirements of optical cables and electrical cables.
In view of the above, it is an object of the invention to provide a cable retainer which can be used in organizing, arranging and routing electrical and optical cables. In particular, the cable retainer should allow for effectively organizing and routing large numbers of electrical cables, e.g., copper wires, and optical cables, e.g., fiber optic cables.
It is another object of the invention to provide a cable organizer employing the cable retainers of the invention. The cable organizer should enable effective cable management in large-scale telecommunications terminals and the like.
Further objects and advantages will become apparent upon reading the following description of the invention and its preferred embodiments.
The objects and advantages of the invention are attained by a cable retainer having a shaft with a top, a bottom, a front, a back and sides. The shaft""s cross section can be oval. A top retention region extends along the top of the shaft. The top retention region admits one or more cables. A side retention region extends along one of the sides of the shaft. The side retention region admits one or more cables. The cables mounted in the top retention region and in the side retention region can be of one type, such as optical cables, or of different types, such as electrical cables and optical cables (optical fibers).
The cable retainer has a first retention mechanism attached to the shaft for restraining the cables within the top retention region. A second retention mechanism is attached to the shaft for restraining the cables within the side retention region.
The first retention mechanism is made up of a stop attached at the top of the shaft and a flexible top tab attached to the back of the shaft. The retention region thus extends along the top from the back of the shaft to the stop. The top tab is advantageously designed to overarch the stop. In addition, the top table can extend all the way to the front of the shaft.
The second retention mechanism is made up of a lip structure attached to the front of the shaft and a flexible side tab extending along the side to the front of the shaft as well. Advantageously, the lip structure has several flanges or lips attached to the shaft. In one embodiment, the lip structure is made up of a top lip attached to the top and a bottom lip attached to the bottom of the shaft. With or without the bottom lip, the top lip preferably has a laterally extending portion.
It is also advantageous when the side tab constitutes a portion of the shaft, i.e., when the tab is a portion of the side of the shaft. The side tab can be attached to the back of the shaft. In one embodiment the side tab has a tab stop at the front. Advantageously, the tab stop has an actuation feature of the type that can be manually operated to flex the side tab.
In one embodiment the placement of the top and side retention regions is such that there is a partial overlapping between them. In this embodiment the cable or cables mounted in the top retention region limit the range of motion of the cables mounted in the side retention region.
It is preferable that at least a portion, e.g., the portion which comes in contact with the cables, and especially with the optical cables be made of a chemically resistant plastic. In fact, the entire cable retainer can be made of a chemically resistant plastic.
The present invention further provides a cable organizer employing the cable retainers. In one embodiment the cable retainers are mounted on the cable organizer by their backs and in a predetermined pattern. The cable retainers are preferably mounted at a predetermined distance from each other. In a preferred embodiment the distance is selected such that the laterally extending portion of the top lip of a cable retainer adjacent to another cable retainer cooperates with the tab stop of this other cable retainer to restrain the cable with the side retention region of this other cable retainer.
The cable organizer of the invention can additionally feature a tray positioned below the cable retainers, as well as any number of other convenient features aiding the user in arranging, organizing and routing the two types of cables.
The various embodiments of the invention are described in detail in the subsequent detailed description with reference to the drawing figures.